Sand filter with rotating vanes

ABSTRACT

The present invention is a media-based fluid filtration system that extends the time between backwashing operations and prevents the agglomeration of filtered particles at the top of the media bed through the use of a plurality of rotating vanes and associated tines that continuously agitate the upper portion of the filtration media to create a fluidized bed. The fluid stream to be filtered is introduced at the top of a generally cylindrical filtration chamber at a tangential angle to induce a helical flow inside the chamber. The chamber contains one or more layers of filtering media such as sand, gravel, or the like below the inlet. The incoming fluid stream makes contact with a plurality of pivotally mounted vanes, causing them to rotate. One or more downwardly extending tines are attached to each blade, extending down from the blade into the top layer of the filtering media. The pressure from the incoming fluid rotates the blades, causing the tines to stir the top layer of the media which prevents filtered particles from agglomerating or caking at the top of the media.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to media-based solid-liquidfilters, and more particularly to a new and improved sand mediafiltering device for efficiently and continuously filtering solids fromliquids in a liquid/solid mixture for longer periods of time with fewerbackwashing operations.

[0003] 2. Description of the Prior Art

[0004] Many agricultural, industrial, and commercial processes andsystems require filtration of the water or other fluids used. Theultimate purpose or use for the water or fluid generally dictates theamount of filtration required. For some operations, filtration ofparticles down to 20 microns is sufficient, while others may requirefiltration down to 5 microns, 1 micron or even less. To address theseneeds, different filtration systems have been developed.

[0005] Screen or wire mesh filters are well known in the art. Suchfilters typically employ one or more layers of woven wire screen ormesh, sometimes having different opening sizes. Water or fluid is passedthrough the mesh which filters out particles larger than the smallestopening sizes of the mesh. Because of their permanent fixation, suchfilters can become easily and quickly clogged, and therefore requireconstant cleaning or backwashing. This kind of constant interruption ofthe filtration process cannot be tolerated in many environments.

[0006] Media-based filters have also been developed which include one ormore layers of different sized media (such as sand or gravel) deployedin a filtration chamber. Water or fluid is passed through the chamber,and the media filters out particles. The media may range in size fromcoarse to fine, depending upon the amount of filtration required, andmay include activated carbon to remove organic materials such asbacteria and the like. Filtered particles accumulate in the media andmust eventually be removed by backwashing.

[0007] For many media-based filters, it is common to backwash three orfour times per day. This causes a disruption in the filtering process,and often requires use of filtered water or fluid to perform thebackwashing operation itself. It is possible to lengthen the timebetween backwashing operations by providing larger filters with moremedia, however large filters may not be appropriate or affordable inmany applications. Unfortunately, media-based filtration systems alsosuffer from a significant drawback posed by the potential foragglomeration or caking of filtered particles at the top of the mediabed, forming a solid layer. When such caking occurs, it may slow or stopthe filtration process until the caked material can be backwashed out.More significantly, if the caked material becomes too thick, it may alsointerrupt or prevent the backwashing process itself.

[0008] It is therefore desirable to provide a media-based fluidfiltration system that is capable of providing filtration for longerperiods of time between backwashes without increasing the size of thesystem, and which prevents the agglomeration of filtered particles atthe top of the media bed.

SUMMARY OF THE INVENTION

[0009] The present invention provides a media-based fluid filtrationsystem that extends the time between backwashing operations and preventsthe agglomeration of filtered particles at the top of the media bedthrough the use of a filtration device that includes a plurality ofrotating vanes and associated tines that continuously agitate the upperportion of the filtration media to create a fluidized bed. In thepresent invention, the fluid stream to be filtered is introduced at thetop of a generally cylindrical filtration chamber at a tangential angleto induce a helical flow inside the chamber. The chamber contains one ormore layers of filtering media such as sand, gravel, gamett, activatedcarbon, or the like below the inlet. The incoming fluid stream makescontact with a plurality of pivotally mounted blades or vanes, causingthem to rotate. One or more downwardly extending tines are attached toeach blade, extending down from the blade into the top layer of thefiltering media. The pressure from the incoming fluid rotates theblades, causing the tines to stir the top layer of the media whereagglomeration or caking is most likely to occur. This agitation preventsfiltered particles from agglomerating or caking at the top of the media.

[0010] It is preferred that the incoming fluid stream be balanced withrespect to the media so that consistent filtration is performed. In thisregard, the incoming fluid stream is preferably introduced through apair of oppositely positioned inlets, multiple pairs of inlets, orthrough a plurality of inlets that are positioned to achieve a balancedinflow.

[0011] The lengths of the tines are such that they penetrate into thetop layer of the filtration media. Although the tines may all be of thesame length, this is not necessary, and in many cases better agitationcan be achieved through the use of tines having several differentlengths so as to stir the media at different depths.

[0012] Depending upon the amount of filtration desired, a single ormultiple layers of filtration media may be provided, ranging from veryfine to very coarse, and anything in between. Different media materialmay also be used including without limitation sand, gravel, gamett andthe like. If control of organic materials is desired, activated carbonmay also be included with or in place of other media.

[0013] The fluid is removed from the present invention through aplurality of filtration nozzles located at the bottom of the vessel.These nozzles are attached to a plurality of hollow removal arms thatcommunicate with the outside of the vessel. Each nozzle is covered by awire mesh filter screen, generally having opening sizes of 10 microns.While nozzle screens having different sized openings may be substitutedto accomplish different levels of filtration, this is more likely to beaccomplished by substituting different media in the vessel itself. Thenozzles and arms are preferably positioned such that they are surroundedby the lowermost layer of the filtration media. In an alternativeembodiment, the nozzles may be deployed below the lowermost layer,separated therefrom by use of a screen or other media support.

[0014] Because of the constant agitation of the upper media into afluidized bed, the filtration system of the present invention avoidsagglomeration of particles, and is capable of performing filtrationoperations for longer periods of time between backwash operations.Comparable filtration systems may require backwashing three or fourtimes daily, while the filtration system of the present invention mayonly require backwashing once per day. Moreover, the backwashingoperation itself is made faster and more efficient with the presentinvention because there is no layer of agglomerated particles to bebroken up or dislodged during the backwashing operation.

[0015] It is therefore a primary object of the present invention toprovide a media-based filtration system having a fluidized upper mediabed that prevents the agglomeration of filtered particles.

[0016] It is also an important object of the present invention toprovide a media-based filtration system that is capable of performingfiltration operations for extended periods of time between backwashoperations because filtered particles do not agglomerate in the mediabed.

[0017] It is a further important object of the present invention toprovide a media-based filtration system having a fast and efficientbackwash operation that is not impaired by any agglomeration of filteredparticles.

[0018] It is a further important object of the present invention toprovide a media-based filtration system having a plurality of rotatableblades above the media bed, with each blade attached to one or moretines that extend into the media bed, such that the tangential inflow offluid into the system rotates the blades causing the tines to agitatethe upper layer of the media bed.

[0019] Additional objects of the invention will be apparent from thedetailed descriptions and the claims herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a front perspective view of one embodiment of thepresent invention.

[0021]FIG. 2 is a detailed perspective view of the rotating blades ofthe present invention.

[0022]FIG. 3 is a detailed sectional perspective view of a dischargenozzle.

[0023]FIG. 4 is a partially cut-away side plan view of the presentinvention.

[0024]FIG. 5 is a top plan view of the present invention showing theinternal structures in phantom lines.

[0025]FIG. 6 is an environmental view showing the invention installed aspart of a fluid filtering system.

DETAILED DESCRIPTION

[0026] Referring to the drawings wherein like reference charactersdesignate like or corresponding parts throughout the several views, andreferring particularly to FIG. 1, it is seen that the invention includesa large vessel 20 having a cylindrical wall 21 defining an internalchamber 24. A central axially aligned upper inlet pipe 27 is provided atthe top of vessel 20 for the normal operation of receiving an incomingfluid stream containing liquid, solids and gasses (“fluid stream”). Acentral, axially aligned lower outlet pipe 28 is provided at the bottomof vessel 21 leading from internal chamber 24 to the exterior for thenormal discharge of filtered fluid. It is to be appreciated that duringperiodic backwash or backflow operations, fluid is introduced at lowerpipe 28 and exits at upper pipe 27.

[0027] Inlet pipe 27 extends into chamber 24 and connectsperpendicularly into a lateral pipe 29 forming a coupling in the shapeof an inverted “T.” The two arms of lateral pipe 29 extend outwardly andterminate in chamber 24 near cylindrical wall 21. The ends 31, 32 ofboth arms are open, allowing fluid to pass from inlet pipe 27 throughlateral pipe 29 and into chamber 24. Elbow or corner pipes are providedon each end 31, 32 of lateral pipe 29 so that fluid entering chamber 24through pipe 29 does so at an angle that is generally tangential tocylindrical wall 21. See FIG. 5. In addition, each end opening 31, 32 ofpipe 29 is tilted slightly downwardly. This tangential, downwardintroduction of fluid results in a downward rotational flow insidechamber 24, creating a slight vortex in chamber 24.

[0028] A balanced incoming fluid flow is desirable so that uniformfiltration can occur. This is accomplished by the pair of oppositelypositioned inlet openings 31, 32. It is to be appreciated that any otherconfiguration of inlet openings that provide a balanced incoming fluidflow may alternatively be used, including multiple pairs of oppositelypositioned openings, or any other suitable arrangement of openings.

[0029] Referring to FIGS. 1 and 2, it is seen that a plurality ofslightly arcuate blades (impellers) or vanes 35 are provided immediatelybelow outlets 31 and 32 of pipe 29. One end of each of blades 35 isattached to an axially aligned central pivot 36. Each blade 35 extendsgenerally radially outwardly away from pivot 36, with the opposite endof each blade 35 terminating near cylindrical wall 21. Blades 35 arepositioned so that the downward, tangential flow entering chamber 24through outlets 31 and 32 makes contact with them. This contact causesblades 35 to rotate about pivot 36 in a circular motion. It is to beappreciated that blades 35 have a generally flat cross section, and maybe straight, but are preferably slightly arcuate in order to respondmore fully to the incoming flow. The amount of curvature of vanes 35 mayrange from none to substantial, depending upon the anticipatedsolids/liquid content of the incoming fluid stream.

[0030] Each of blades 35 is provided with one or more downwardlyextending rods or tines 37 that move in a circular path in accordancewith the rotation of each blade. Tines 37 are preferably placed atdifferent distances from the ends of the various blades 35 so that adifferent circular path is defined by each of tines 37. When blades 35are in motion, tines 37 rake the top of the media bed 40 inside chamber24 so as to prevent caking or the formation of a blanket from theagglomeration or solidification of particulates (particularly organicmaterials) on the top of the filter bed. A media bed 40 made up of sandor garnett (depending upon the level of filtering desired) is providedin chamber 24, which causes filtering through one or more levels offiltration media which may be provided in varying depths of thickness.It is to be appreciated that the exact grade, depth and type of mediaselected may be varied widely depending upon the ultimate filtrationgoal to be achieved. A typical exemplary media bed might include ¾″ peagravel at the bottom, garnett in the middle, and sand (feldspar #120) atthe top. Variations might include providing activated carbon in place ofor in addition to the gamett in the middle to control bacteria. Thegrade 120 feldspar might be expected to provide filtration down to 10microns, but if greater filtration is desired, it might be replaced witha higher grade feldspar (100, 80 or higher) to achieve filtration downto 5 or even 1 micron.

[0031] The fluid stream passes through the media 40, and enters thelower region of vessel 24. Here the filtered fluid exits vessel 20through a plurality of wedge-wire screens. As shown in FIGS. 1 and 3, aplurality of hollow arms 51 are provided in the lower section of chamber24, each arm being in fluid communication with exit pipe 28. Arms 51 arepositioned above the floor of vessel 20 so as not to become buried insettling sediment, but are designed to be surrounded by media (e.g.,coarse ¾″ pea gravel). One or more removal nozzles 55 are provided oneach of arms 51, and each removal nozzle includes a wedge-wire screen 58having micronic openings. See FIG. 3. Different screens having differentsized openings may be utilized with nozzles 55 depending upon the levelof filtration desired, although changes in filtration are ordinarilyaccomplished by using different media.

[0032] The raking action of the tines 37 caused by the rotation ofblades 35 results in a more effective filtration system with longerperiods between backwashing operations because the agitation caused bythe tines 37 keeps the solids in suspension so that they do notagglomerate and blanket over the media. Backwashing time is alsominimized, and lesser backwash water volume is required. In particular,the improved system of the present invention avoids unnecessary downtime for maintenance in opening the tank and untimely replacement of themedia.

[0033] When a selected differential pressure is reached between incomingand exiting fluid (e.g. from 10-15 p.s.i.g.), it is appropriate for theunit to be backwashed. The backwash water may be from a municipal watersupply, recycled plant water, or other appropriate source, and isnormally applied at around 30 p.s.i.g. in order not to wash out themedia itself. In the backwash operation, the flow of fluid throughvessel 20 is reversed, with the outgoing dirty fluid exiting throughpipe 27 directed to a designated drain or collection sump.

[0034] It is to be appreciated that different versions of the inventionmay be made from different combinations of the various featuresdescribed above. In particular, any number of pipes 29 with any numberof elbow openings 31, 32 may be provided; that any suitable number ofblades 35 may be provided, and that any suitable number of tines 37 maybe provided on each blade 35. In addition, the curvature of blades 35may range from none to substantial. Similarly, any suitable number ofarms 51 may be provided, and any suitable number of exit nozzles 55 maybe provided on each arm 51. The diameter and length of inlet and outletpipes 27 and 28 may also be varied according to the expected fluidconditions and the size of vessel 20.

[0035] It is to be understood that variations and modifications of thepresent invention may be made without departing from the scope thereof.It is also to be understood that the present invention is not to belimited by the specific embodiments disclosed herein, but only inaccordance with the appended claims when read in light of the foregoingspecification.

1. A fluid filtration system comprising: a. a vessel having acylindrical side wall, and upper and lower end walls forming an interiorchamber; b. filtration media disposed in said chamber such that there isan open space at the top thereof; c. an inlet in said upper end wall influid communication with a plurality of openings for introducing fluidunder pressure into the open space of the chamber at an angle that istangential to said cylindrical side wall inducing a helical flow; d. aplurality of pivotally attached radially spaced apart axially-extendingblades positioned in the open space below said openings such that thefluid flowing into the chamber from said openings comes into contactwith said blades; e. at least one downwardly extending tine attached toeach of said blades, said tine extending from said blade into an upperportion of said filtration media; and f. at least one outlet at thelower end of said chamber in communication with the exterior of saidvessel, said outlet including a filtration screen.
 2. The fluidfiltration system of claim 1 wherein said outlet includes a plurality ofhollow arms with each arm supporting at least one nozzle, and whereineach nozzle includes a detachable filtration screen.
 3. The fluidfiltration system of claim 1 wherein the length of each of said tines isthe same.
 4. The fluid filtration system of claim 1 wherein said tinesare of differing lengths.
 5. The fluid filtration system of claim 1wherein each of said blades is straight.
 6. The fluid filtration systemof claim 1 wherein each of said blades has an arcuate shape.
 7. Thefluid filtration system of claim 1 wherein said inlet includes anaxially oriented first pipe having a first end in fluid communicationthe exterior of said vessel, and an opposite end terminating into and influid communication with a second perpendicularly oriented pipe locatedinside said vessel, said second pipe extending across said chamber andhaving openings at opposite ends thereof.
 8. The fluid filtration systemof claim 7 wherein each of the end openings of said second pipe is bentat an angle that is tangential to said cylindrical wall.
 9. The fluidfiltration system of claim 8 wherein each of said end openings is angledslightly downwardly to induce a helical fluid flow inside said vessel.10. A fluid filtration system comprising: a. a vessel having acylindrical side wall, and upper and lower end walls forming an interiorchamber; b. filtration media disposed in said chamber such that there isan open space at the top thereof; c. an inlet in said upper end wall influid communication with a plurality of openings for introducing fluidunder pressure into the open space of the chamber at an angle that istangential to said cylindrical side wall inducing a helical flow whereinsaid inlet includes an axially oriented first pipe having a first end influid communication the exterior of said vessel, and an opposite endterminating into and in fluid communication with a secondperpendicularly oriented pipe located inside said vessel, said secondpipe extending across said chamber and having openings at opposite endsthereof; d. a plurality of pivotally attached radially spaced apartaxially-extending blades positioned in the open space below saidopenings such that the fluid flowing into the chamber from said openingscomes into contact with said blades; e. at least one downwardlyextending tine attached to each of said blades, said tine extending fromsaid blade into an upper portion of said filtration media; and f. atleast one outlet at the lower end of said chamber in communication withthe exterior of said vessel, said outlet including a filtration screen.11. The fluid filtration system of claim 10 wherein each of the endopenings of said second pipe is bent at an angle that is tangential tosaid cylindrical wall.
 12. The fluid filtration system of claim 11wherein each of said end openings is angled slightly downwardly toinduce a helical fluid flow inside said vessel.